Process for preparing polyurethane foams employing tertiary amine catalysts



United States Patent PROCESS FOR PREPARING POLYURETHANE FOAMS EMPLOYINGTERTIARY AMINE CATALYSTS Franzkarl Brochhagen, Odenthal Bezirlr Koin,and Karl E. Miiller, Leverkusen-Bayerwerk, Germany, assignors toFarbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany, acorporation of Germany No Drawing. Application August 9, 1954 Serial No.448,746

Claims priority, application Germany August 19, 1953 1 Claim. (Cl.260-25) The present invention relates to foamed products based onpolyurethanes and to a process for producing the same.

It is known to produce foamed products based on polyurethanes frompolyesters and diisocyanates in the presence of activators.

When activators based on tertiary amines are used, the elastic foamedproducts thus produced exhibit a certain characteristic odour. Besides,the stability of the conventional activator mixtures is unsatisfactory,which renders it necessary for the activator mixture to be carefullysupervised when the production is carried out continuously, thestability of said mixture being at most 4 hours.

An object of the present invention is to provide improved and odourlessfoamed products based on polyurethanes.

Another object is to provide a new process for the production ofimproved and odourless foamed products from polyesters and diisocyanatesin the presence of activators.

A still further object is to provide new and stable activators mixturesfor the manufacture of improved and odourless foamed products based onpolyurethanes.

These and further objects are attained in accordance with the presentinvention by reacting a polyester and a diisocyanate in the presence ofa tertiary amine containing at least one group able to react withisocyanates. Tertiary amines containing reactive groups able to reactwith isocyanates activate the foaming process and react at the same timewith isocyanate groups, thus making it possible to produce odourlessproducts. Because of the miscibility of the new activators with waterthe activator mixtures are stabilized.

Representative examples of groups reacting with isocyanates are amino,hydroxyl, carboxyl and mercapto groups. Suitable tertiary aminescontaining such reactive groups include, inter alia, methyldiethanolamine, N- diethyl ethanolamine, N-diethyl aminoacetic acid,methyl iminodipropionic acid and N-methyl dipropylene triamine.

The invention is further illustrated by the following examples withoutbeing restricted thereto, the parts being by weight.

Example 1 100 parts of a polyester obtained from 1 mol of adipic acidand 1.2 mols of diethylene glycol are mixed with.

ice

3 parts of methyl diethanolamine and 2 parts of water.

Thereupon 35 parts of toluylene diisocyanate are added and the mixtureis stirred.

After hardening an elastic, odourless, foamed. product of a unit weightof 60 kg./m. is obtained.

Example 2 Example 3 100 parts of a polyester obtained from 1 mol ofadipic acid, 1 mol of diglycol and 0.1 mol of trimethylol propane aremixed with 5 parts of methyl iminodipropionic acid and 3 parts of water.After adding 45 parts of toluylene diisocyanate the mixture is stirred.

An elastic foamed product of a unit Weight of 40 kg./m. is obtained.

Example 4 80 parts of a polyester obtained from 2.5 mols of adipic acid,0.5 mol of phthalic acid and 4 mols of hexanetriol are mixed with 20parts of a polyester obtained from 1.3 mol of adipic acid and 1 mol ofhexanetriol, and 1.3 part of butylene glycol and 10 parts of siliceouschalk. After adding 1 part of N-methyl propylene d1- amine and 2 partsof sulfonated castor oil (water content: 50%) and mixing 55 parts oftoluylene diisocyanate are added.

After intimately mixing a hard foamed product is obtained, which has aunit weight of kg./m. and is practically odourless.

What we claim is:

A process of producing a foamed plastic from (1) a hydroxyl polyesterprepared by the esterification of a dicarboxylic acid with a polyhydricalcohol, (2) an organic diisocyanate, (3) an activator, and (4) water,which comprises adding said organic diisocyanate to a mixture comprisingsaid hydroxyl polyester, water and the activator, said activator being acompound containing (a) at least one tertiary amino group, and (b) atleast one group containing reactive hydrogen capable of reacting With anisocyanate and selected from the class consisting of amino, hydroxyl,and carboxyl groups; and thereafter stirring the resultant mixture,whereby a foamed plastic is formed.

References Cited in the file of this patent UNITED STATES PATENTS2,597,025 Orth May 20, 1952 2,602,783 Simon et al. July 8, 19522,625,531 Seeger Jan. 13, 1953 2,625,535 Mastin et al Jan. 13, 19532,650,212 Windemuth Aug. 25, 1953 2,683,727 Mastin et a1 July 13, 19542,764,565 Hoppe et a1 Sept. 25, 1956

